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Introduction to human anatomy. Introduction. A strong, yet light, internal support for the human body The skeleton is adapted for the protection, locomotor, and manipulative functions The upright stance increases the ability of the skeletal muscle to resist gravity. Introduction.
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Introduction • A strong, yet light, internal support for the human body • The skeleton is adapted for the protection, locomotor, and manipulative functions • The upright stance increases the ability of the skeletal muscle to resist gravity
Introduction • The skeleton maintains its upright position through a series of compensating curves • The skeleton accounts for approximately 20% of the body mass • The 206 bones of the body are grouped into the axial and appendicular skeleton
Axial skeleton Forms the long axis of the body 80 bones in three major regions skull vertebral column bony thorax Ribs Sternum Appendicular Bones of upper & lower extremities and girdles 126 bones in three major regions Girdles Shoulder girdle Pelvic girdle upper extremity lower extremity Introduction
The Skull • The skull is the body’s most complex bony structure • It is formed by two sets of bones, the 8 cranial bones and the 14 facial bones • These 22 bones combine to form the cranial cavity and the facial features • In addition, there are 3 bones in each inner ear to assist in sound transmission
The Skull: Introduction • The bones of the skull provide . . . • A case to house the brain, the cranium • A framework for the face • Cavities to house the organs of sight, taste, and smell • Passages for air and food • Attachment sites for the teeth • Attachment sites for muscle
The Skull: Introduction • Most bones of the skull are flat bones • Except for the mandible, all bones are firmly united by interlocking sutures • The major sutures of the skull are . . . • Coronal (Between Frontal & Parietal) • Sagittal (Between Parietal bones) • Squamosal (Between Parietal & Temporal) • Lambdoidal (Between Parietal & Occipital) • Other skull sutures connect facial bones and are named after these structures
________ ________ ________ Sagittal
Coronal Lambdoid Squamous
Overview of Skull Geography • Facial bones form the anterior aspect • The cranial bones enclose the brain
Vault • The cranial vault or calvaria forms the superior, lateral, and posterior aspects of skull • The cranial base forming the inferior aspect of skull
Cranial Base • Cranial base forms the skull’s inferior aspect • Three prominent ridges divide the base into fossae • The brain rests on these cranial fossae completely enclosed by the cranial vault • The brain occupies the cranial cavity
Cavities of the Skull • In addition to the large cranial cavity there are many smaller cavities • Middle and inner ear cavities • Nasal cavity • Orbits of the eyes • Several bones contain air filled sinuses • Sinuses surrounding the nasal cavity are referred to as the paranasal sinuses
Study Note • As you read about the bones of the skull, locate each bone on the different skull views in Figures 7.2, 7.3, 7.4 • The skull bones and their important markings and features are summarized in Table 7.1 on pages 213-214
Cranium • The 8 cranial bones include; 2 parietal, 2 temporal frontal, occipital, sphenoid, ethmoid • Cranium is self- bracing allowing the bones to be thin, yet strong
Frontal bone • Forms the anterior portion of the cranium, the forehead, roofs of the orbits, and most of the anterior cranial fossa
Frontal bone - landmarks • Frontal squama • Supraorbital margins • Supraorbital foramen • Orbits • Anterior cranial fossa • Glabella • Frontal sinuses
Parietal bones Parietal • Forms most of the superior & lateral aspects of the skull • Articulates with other cranial bones to form four major sutures
Parietal bones - landmarks • The four largest sutures cranial sutures, Coronal, Sagittal, Lambdodial, Squamosal
Occipital bone • Forms most of the posterior wall and base of skull • Articulates with parietal & temporal • Joins w/ sphenoid in the cranial floor • Forms internal walls of posterior cranial fossa
Occipital bone - Ext. landmarks • Foramen magnum, Occipital condyles, External occipital protuberance, Nuchal lines, External occipital crest
Occipital bone - Int. landmarks • Hypoglossal canal, Posterior cranial fossa
Temporal Bone • Forms the infero-lateral aspects of the skull • Parts of the cranial floor • Divided into four regions; squamous tympanic, mastoid, and petrous-(int)
Temporal Bone • The internal petrous region contributes to the cranial base • The petrous region and the sphenoid bone form the middle cranial fossa
Temporal Bone - landmarks • Zygomatic process • Meets the zygomatic bone • Forms the cheek • Mandibular fossa • Receives condyle of mandible
Temporal Bone - landmarks • External Auditory Meatus • Middle and inner ear • Styloid process • Muscle of tongue • Mastoid process • Muscles of neck
Temporal bones - landmarks • Jugular foramen • Entry point for the Jugular artery • Internal acoustic meatus • Entry point for the auditory nerve Jugular Foramen
Temporal bones - landmarks • Stylomastoid foramen • exit for facial nerve • Carotid canal • entrance for the carotid artery which supplies blood to cerebral hemispheres
Sphenoid bone • Bone spanning the width of middle cranial fossa • Articulates as central wedge of all cranial bones • Consists of central body and three processes; greater and lesser wings and pterygoid process (pos. view)
Sphenoid - landmarks • Sella turcica (enclosure for pituitary gland) • Optic foramina (passage of optic nerves) • Superior orbital fissure (Nerves III, IV, V enter orbit) • Foramen rotundum & ovale (Cranial Nerve V to face) • Foramen spinosum (Middle meningeal artery)
Ethmoid bone • Forms most of the area between the nasal cavity & orbits of eyes • Lies between nasal bones & sphenoid • Complex shape gives rise to nasal septum, sinuses and cribiform plate
Ethmoid bone - landmarks • Cribiform plates • Forms roof of nasal cavity • Olfactory formina • Olfactory nerves enter brain • Crista galli • Attachment of the dura mater which secures brain in cavity
Ethmoid bone - landmarks • Perpendicular plate • Forms superior part of nasal septum • Lateral mass • House ethmoid sinuses • Nasal concha • Project into nasal cavity • Orbital plates • Medial walls of orbits
Facial bones • Consists of 14 bones w/ only mandible and vomer unpaired • Others include maxillae, lacrimals, nasals, zygomatics, inferior nasal conchae, and palatines (not pictured)
Mandible • Forms the lower jaw • Largest, strongest bone of the face • It has a body and two upwardly projecting sections called rami • Houses lower dentition
Mandible - landmarks • Mandibular angle • Mandibular notch • Coronoid process • Mandibular condyle • Alveolar margin • Mandible formina • Mental formina • Ramus of mandible
Maxillary bone • Forms upper jaw and central portion of facial skeleton • Fused medially • Articulates with all facial bones except mandible • Upper dentition • Forms 2/3 of hard palate of the mouth Zygomatic process Maxillary bone
Maxillary bones - landmarks • Alveolar margin • Upper dentition • Frontal process • Forms lateral aspects of nose • Zygomatic process • Articulates with zygomatic bone • Maxillary sinuses • (Fig. 7.11)
Maxillary bones - landmarks Palatine Process • Palatine processes • Forms roof of mouth • Incisive fossa • Passage of nerves and blood vessels • Infraorbital foramen • Infraorbital nerve and blood vessel to face
Maxillary bones - landmarks • Inferior orbital fissure • Located deep within the orbit • Permits passage of the zygomatic nerve, maxillary nerve, and blood vessels to reach face
Zygomatic bones • Commonly called the cheekbones • Form prominences of cheeks and inferolateral margins of orbits • Articulate with the Zygomatic process of temporal bone and Zygomatic process of maxallae Zygomatic Process of Temporal Zygomatic bone
Nasal bones • Forms bridge of the nose • Thin, rectangular shape • Fused medially • Articulate with the frontal bone and maxillary bones laterally • Nasal cartilages • (Fig. 6.1)
Lacrimal Bones • Forms part of the medial border of each orbit • Articulates with frontal, ethmoid & maxillae • Forms part of Lacrimal fossa • Permits tears to drain from orbit to nasal cavity
Lacrimal Bones • Lacrimal fossa • Permits tears to drain from orbit to nasal cavity
Palatine bones • The horizontal plates forms the posterior portion of hard palate • Vertical plate forms part of the posterolateral wall of nasal cavity and a small portion of orbit
Palatine bones - landmarks • Horizontal plate • Posterior section of hard palate • Vertical plate • Part of the posteriolateral walls of nasal cavity • Orbital surface • Part of inferior medial aspect of orbit
Vomer • Forms part of the nasal septum • Discussed with the nasal cavity
Vomer - landmarks • Plow shape • Divides nasal septum into right and left parts
Inferior Nasal Conchae • Form lateral walls of nasal cavity • Project medially from the lateral walls of nasal cavity • Largest of nasal conchae